U.S. patent number 5,088,779 [Application Number 07/573,981] was granted by the patent office on 1992-02-18 for door latch release mechanism.
This patent grant is currently assigned to Harcor Security Seals Pty Limited. Invention is credited to Frank Weiss.
United States Patent |
5,088,779 |
Weiss |
February 18, 1992 |
Door latch release mechanism
Abstract
A door latch release mechanism has a housing adapted for
mounting in a door jamb, a striker mounted on a shaft in the
housing for pivotal movement between a door lock tongue engagement
position and a door lock tongue release position, and a stop
mounted in the housing. The stop has a portion capable of
contacting the striker so as to latch the striker and prevent
pivoting thereof from the door lock tongue engagement position.
This portion of the stop is generally semi-circular in cross
section. The stop is rotatable on its axis so that rotation of the
stop to an effective extent releases the striker.
Inventors: |
Weiss; Frank (New South Wales,
AU) |
Assignee: |
Harcor Security Seals Pty
Limited (New South Wales, AU)
|
Family
ID: |
3774137 |
Appl.
No.: |
07/573,981 |
Filed: |
August 27, 1990 |
Foreign Application Priority Data
Current U.S.
Class: |
292/341.16;
292/201 |
Current CPC
Class: |
E05B
47/0047 (20130101); Y10T 292/1082 (20150401); Y10T
292/699 (20150401) |
Current International
Class: |
E05B
47/00 (20060101); E05B 015/02 () |
Field of
Search: |
;292/341.16,201,DIG.60,244 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
206324 |
|
Jul 1949 |
|
AU |
|
125977 |
|
Sep 1900 |
|
DE |
|
1026193 |
|
Mar 1958 |
|
DE |
|
1178110 |
|
Jan 1970 |
|
GB |
|
Primary Examiner: Smith; Gary L.
Assistant Examiner: Boucher; Darnell
Attorney, Agent or Firm: Lackenbach, Siegel, Marzullo &
Aronson
Claims
I claim:
1. A door latch release mechanism having:
a housing adapted for mounting in a door jamb;
a striker mounted on a shaft in the housing for pivotal movement
between a door lock tongue engagement position and a door lock
tongue release position; and
a longitudinally extending stop mounted in the housing and having a
portion capable of contacting the striker so as to latch the
striker and prevent pivoting thereof from the door lock tongue
engagement position, the stop is rotated by electromagnetic means
on its longitudinal axis, the shaft having its axis parallel to the
axis of the stop and the striker having an elongated edge parallel
to each axis, said portion of the stop being generally
semi-circular in cross section, wherein said portion of the stop is
adapted to engage substantially the whole of the elongated edge in
a tangential manner, so that rotation of the stop to an effective
extent releases the striker.
2. A door latch release mechanism as claimed in claim 1, wherein
the electromagnetic means comprising an armature attached to the
stop and a core magnetised by a surrounding coil, the armature and
the coil each having an inclined surface capable of attraction to
each other in response to the application of electrical energy.
3. A door latch release mechanism as claimed in claim 2, wherein
the armature is reversibly attached to the stop and reversing of
the armature reverses the direction of rotation of the stop.
4. A door latch release mechanism as claimed in claim 3, which
includes means to bias the stop towards the position where the
striker is released, the bias means being chosen from the group
consisting of:
(a) a return spring mounted on the stop.
5. A door latch release mechanism as claimed in claim 4, wherein
the housing is a chassis having a cover the removal of which
permits access to the armature and/or the coil.
6. A door latch release mechanism as claimed in claim 5, wherein
there is attached to the chassis a face plate having an inclined
surface adapted to depress a dead latch button on the door
lock.
7. A door latch release mechanism as claimed in claim 6, wherein
the chassis is made of mild steel.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to door locks. In particular, this
invention is concerned with a door latch release mechanism in which
a pivotal striker or keeper is latched by a stop and releasable by
rotation of the stop. In one embodiment, the invention includes an
arrangement whereby the stop may be energised electrically to
release the striker or energised electrically to lock the striker
by use of a reversible armature or a similar arrangement.
2. Description of the Prior Art
Electrically operated door latch release mechanisms mounted on door
frames and the like for locking or unlocking doors from remote
locations--such as in security buildings--are known. There are many
problems associated with known mechanisms. These include the
failure of many prior art mechanisms to operate when a load is
applied to the door. For instance, if a wind exerts force against
the door or if a person leans against the door, the relationship
between the striker and the latch may become distorted, so that
deactivation of the latch does not free the striker.
Another problem arises from attempts at forced entry. In some prior
art mechanisms, the striker is latched by a relatively small pin or
the like and the exertion of force can cause this pin to bend or
break, thus releasing the door in an unauthorised situation.
Many prior art mechanisms are difficult to clean or service because
they lack ready access to working parts. Many are constructed with
insufficient chassis strength. There is a need for a mechanism
which can permit access to parts and which has a strong
chassis.
In addition to the above, it is desirable to provide a door latch
release mechanism which has a dual mode of operation, so that the
mechanism can be converted from one which is latched when energised
to one which is unlatched when energised. Dual mode operations have
been disclosed in U.S. Pat. No. 4,211,44 and PCT Application No.
PCT/SE84/00363, published under No. WO 86/02690, for example.
However, there is a need for dual mode operations which are simple
to convert and which minimise the risk of error on the part of the
person effecting the conversion.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a door latch release
mechanism which is capable of overcoming or substantially
alleviating some or all of the problems referred to above. It is a
further object of the invention to provide a door latch release
mechanism which may be adapted easily to conversion from the
"energised locked" configuration to the "energised unlocked"
configuration.
Accordingly, this invention comprises a door latch release
mechanism having:
a housing adapted for mounting in a door jamb;
a striker mounted on a shaft in the housing for pivotal movement
between a door lock tongue engagement position and
a door lock tongue release position; and
a stop mounted in the housing and having a portion capable of
contacting the striker so as to latch the striker and prevent
pivoting thereof from the door lock tongue engagement position, the
portion of the stop being generally semi-circular in cross section
and the stop being rotatable on its axis so that rotation of the
stop to an effective extent releases the striker.
DESCRIPTION OF PREFERRED EMBODIMENTS
Preferably, the stop is rotated by electromagnetic means comprising
an armature attached to the stop and a core magnetised by a
surrounding coil, the armature and the coil each having an inclined
surface capable of attraction to each other in response to the
application of electrical energy. In this embodiment, the armature
is not affected by gravity and the forces acting on the armature
are identical for left hand and right hand doors, which affords the
mechanism of the present invention added advantages over the prior
art.
In an especially preferred embodiment, the armature is reversibly
attached to the stop; reversing of the armature changes the
direction of rotation of the stop, thus enabling conversion of the
mechanism from a configuration where activation of the armature
latches the striker, to a configuration where activation of the
armature unlatches the striker. The conversion may be effected
within a few seconds and has significant advantages in enabling the
reduction of the amount of stock carried by locksmiths.
As illustrated in the Drawings discussed below, the shaft on which
the striker is mounted preferably has its axis parallel to the axis
of the stop, the striker has an elongated edge parallel to each
axis and the portion of the stop is adapted to engage substantially
the whole of the elongated edge. This arrangement adds strength to
the latching of the striker and reduces wear along the site of
engagement, so that the permissible loading of the door is
increased.
In addition, the elongated edge of the striker is preferably
tangential to the circumference of the stop, so that attempts at
forced entry would not achieve release of the door, unless the
force applied is so great that the mechanism itself breaks.
The striker should be biassed away from the stop, so that release
of the striker causes it to pivot on the shaft. A return spring may
be provided for this purpose.
Similarly, the stop should be biassed towards disengagement of the
striker. This may be accomplished by a return spring, which must
oppose, for example, the magnetic force generated by the coil.
As an alternative, rotary magnets may be located one at each end of
the stop. The magnets act in opposing directions and may be
operated by a change-over switch. Because the spring opposing the
magnetic force of the coil can be omitted in this embodiment, the
operating force may be increased. This can enhance reliability and
operation under low voltage conditions. In addition, with this
configuration it is possible to seal the striker/armature/coil unit
and to effect reversal of rotation of the stop by changing the
electrical connections to the rotary magnets.
Instead of using a return spring or a pair of rotary magnets as
described above, the stop may be motor driven. If geared motors are
used, the force on the stop may be increased to such an extent that
the door lock will remain operational despite external forces
exerted on the door--such as a strong wind or a human body.
The housing is preferably made of a mild steel bar split unevenly
on both ends and bent into two hat shaped sections of different
depth (or manufactured of two separate bars joined together by
welding or brazing), so that a face plate with one inclined face
for the depression of dead latch buttons can be attached over the
full length of the chassis. This configuration affords a proper
bearing surface and gives added strength.
The chassis may be provided with a cover, the removal of which may
permit cleaning and servicing as well as access to the armature
and/or the coil.
In a situation where it is desired to change the voltage to be
applied to the mechanism, the coil which is wholly contained within
the chassis and accessible as described, may be replaced in a
relatively simple operation, rather than having to discard the
whole mechanism.
The coil magnetised core which may be of circular or square cross
section with one inclined face can be screwed to one end of the
chassis and forms a part of a magnetic path. The armature,
preferably of trapezoidal cross section, is fastened to the stop
which passes through the flanks of the chassis. Activation of the
armature causes a clockwise or anticlockwise rotation of the stop
if the coil is energised or de-energised. Once the stop has rotated
to a sufficient extent, the edge of the striker is released and the
striker pivots to free the door lock tongue.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the Drawings.
It is to be understood, however, that the Drawings are for the
purposes of illustration only and are not to be interpreted as
limiting on the scope of the invention.
In the Drawings:
FIG. 1 is a sectional side view of an embodiment of the
invention;
FIG. 2 is a sectional plan view of the core and coil along the
lines A--A of FIG. 1 and viewed from above;
FIG. 3 is an elevation of the lower part of the embodiment in FIG.
1 in direction B, with the cover removed;
FIG. 4 is a cross section of the latching mechanism viewed from
above;
FIG. 5a is a sectional plan view along the lines A--A of FIG. 1 and
viewed from below; FIGS. 5b and 5c show the armature in two
configurations; and
FIG. 6 details the operation of the striker mechanism.
DETAILED DESCRIPTION
Referring first to FIG. 1, a steel bar 1 of rectangular
cross-section is split and bent into two hat shaped sections of
different depth 2 and 3 so that a chassis is formed to which a face
plate 4 can be fastened by screws 5. Face plate 4 has one inclined
face (refer FIG. 2) for the operation of dead latch push
buttons.
Two compartments 6 and 7 are formed by the chassis and both
compartments are easily accessible after removal of cover 8 held by
screw 9.
Compartment 6 contains electromagnetic parts for the operation of
the latch release. Compartment 7 contains the electrical parts for
monitoring the state of the latch release, although these parts
have been omitted from the Drawings.
Steel bar 1 includes flanks 10 and 11 which define between them a
central compartment containing striker or tongue release 12 (refer
FIG. 4) pivotally mounted on shaft 13 and held by spring tension
(the spring is not shown) against thrust plate 14 so as to engage
tongue 15 of an adjacent door lock. Elongated ground edge 16 of
striker 12 is opposed by the solid part of stop 17 (refer FIGS. 1
and 4) and thus is prevented from rotation about shaft 13, unless
stop 17 rotates clockwise by approximately 20 degrees to allow edge
16 to pass through the centre of stop 17.
Rotation of stop 17 is accomplished by armature 18 (refer FIGS. 3,
5a and 5b) fastened to stop 17. The movement of armature 18 is
limited by projections 19 and 20 (FIGS. 1 and 5a). Armature 18 has
a trapezoidal cross section opposed by the inclined face of core 21
(FIGS. 1 and 2) so that a diminishing air gap is created between
armature 18 and core 21 if coil 22 (FIGS. 1, 2 and 3) is energised.
Movement of armature 18 is opposed by torsion spring 23 (FIG.
1).
Referring especially to FIG. 6, striker 12 pivoted around shaft 13
is prevented from rotating in the direction of the arrow shown by
stop 17 resting in bearings 34. Stop 17 has a centre portion of
semi-circular cross-section. The latched condition of striker 12
thrusting against the door tongue (no shown in this Figure)
prevents the opening of the door.
Armature 18 is fastened by pin 26 to stop 17 and is attracted to
the inclined surface of core 21 when magnetised by the coil
surrounding it (not shown in this Figure), thus rotating stop 17 in
the direction of the arrow shown. This rotation in turn releases
striker 12 and allows it to pivot about shaft 13.
By withdrawing armature 18 from pin 26 and inserting armature 18
the opposite way, and rotating it by approximately 180 degrees,
(refer FIG. 5c) the direction of rotation of stop 17 can be
changed, thus locking striker 12 if the coil surrounding core 21 is
energised. In this configuration, the torque of spring 23 should be
reversed by changing the engagement point of one of its ends. In
addition, screw 24 (FIG. 1) should be slackened and core 21 should
be rotated by 160 degrees (being 180 degrees less the operational
movement of 20 degrees).
* * * * *